Motion-converting gearing

ABSTRACT

A gearing for converting a constant rotation of its drive shaft to an intermittent rotation of its driven shaft, in which the driven shaft may be stopped and positively locked during each complete revolution of the drive shaft for any predetermined period which may last from a momentary stop to one amounting to a considerable angular distance of each revolution of the drive shaft. The transition from the stopped position to the normal speed of the driven shaft occurs very gradual and without jerks, the locking action upon the driven shaft is attained without any additional locking means, and the entire gearing is of a very simple and inexpensive construction.

United States Patent Buchsteiner, deceased et al.

[ 3,656,362 Apr. 18,1972

MOTION-CONVERTING GEARING Hans Buchsteiner, deceased, Lindengen; HubertKowllslti, Untere Schloss- Strasse 36, 7071 Alfdorf, all of GermanyFiled: Nov. 9, 1970 Appl. No.: 87,885

Inventors:

Foreign Application Priority Data Nov. 8, [969 Germany ..P i9 56 250.6

U.S. Cl ..74/393, 74/84 Int. Cl v ..Fl6h 35/02 Field of Search ..74/84,393

References Cited UNITED STATES PATENTS l0/l953 Wildhaber ..74/393FOREIGN PATENTS OR APPLICATIONS 1,114,409 l2/l955 France ..74/393Primary Examiner-Milton Kaufman Attorney-Craig, Antonelli & HillABSTRACT A gearing for converting a constant rotation of its drive shaftto an intermittent rotation of its driven shaft, in which the drivenshaft may be stopped and positively locked during each completerevolution of the drive shaft for any predetermined period which maylast from a momentary stop to one amounting to a considerable angulardistance of each revolution of the drive shaft. The transition from thestopped position to the normal speed of the driven shaft occurs verygradual and without jerks, the locking action upon the driven shaft isattained without any additional locking means. and the entire gearing isofa very simple and inexpensive construction,

6 Claims, 9 Drawing Figures MOTION-CONVERTING GEARING The presentinvention relates to a gearing for convening the constant rotation ofits drive shaft to an intermittent rotation of its driven shaft. Morespecifically, it is an object of the invention to design such amotion-converting gearing so as to comply with all of the followingrequirements:

1. During each complete revolution of its constantly rotating driveshaft, the driven shaft of this gearing should be stopped entirely;

2. This stopping period of the driven shaft should be maintainedaccurately for any desired length of time;

3. During this stopping period, the driven shaft should be positivelylocked so as to prevent any movement thereof not only while the driveshaft continues to rotate but also if during this period the drive shaftalso stops;

4. The transition from the common rotation of the driving and drivenshafts of the gearing to the deceleration and stop of the driven shaftand the transition from the stop and acceleration of the driven shaft tothe common rotation of both shafts should occur smoothly without anyjerk; and

5. The gearing should be of a simple construction, as wearresistant aspossible, and capable of being subjected to relatively heavy loads.

The motion-converting gearings of the type as first mentioned abovewhich were disclosed prior to this invention have the disadvantage thatthey only comply with some of the above-mentioned requirements. Thus,for example, the US. Pat. No. 2,656,731 discloses such a gearing whichcomprises a drive shaft on which a so-called mutilated drive gear ismounted which is provided with gear teeth only on a circular arc of itscircumference. The drive shaft further carries a disk on which twoanti-friction rollers are mounted, the parallel axes of which aredisposed on diametrically opposite sides of the drive shaft and areequally spaced from the axis of this shaft. The driven shaft of thisgearing carries a normal circular gear wheel with gear teeth on itsentire circumference which is driven as long as its teeth are inengagement with the teeth of the mutilated drive gear. This driven shaftfurther carries a crank arm which projects from one side of this shaftand is provided with two parallel guide grooves at the opposite sides ofan equally spaced from the axis of the crank arm and the open ends ofeach of these guide grooves are spaced at different distances from thedriven shaft. During the period of each revolution of the drive gear inwhich its toothless part is out of engagement with the teeth of the gearwheel on the driven shaft, one roller on the drive shaft will enter theouter end of one guide groove and will then roll along the same, whileat the same time with this entry of the first roller the other rollerwill leave the outer end of the other guide groove after rolling alongthe same. Therefore, the time when one roller leaves one guide groovecoincides with the time when the other roller enters the other guidegroove. Although the driven shaft of this known gearing will once bestopped at this time during each revolution of the drive shaft, thisstop will only be momentary and the next teeth of the driven shaft willthen again be started immediately. Therefore, this gearing does notpermit the driven shaft to remain in a stopped position for a certainlength of time, for example, during a period in which the drive shaftturns about an angle of up to 30 during one complete revolution thereof.Although the stopped position of the driven shaft might be extended soas to last for a certain length of time by the provision of a specialclutch mechanism in the nature of a jaw clutch which disengages the cammember on the driven shaft from the rollers on the drive shaft at themoment when the driven shaft is stopped, such a mechanism is ratherexpensive and also, while it may be utilized for attaining longer stopperiods of the driven shaft which may last, for example, for severalrevolutions of the drive shaft, it is not capable of attaining shorterstop periods of, for example, up to 30 of one revolution of the driveshaft. By making the associated gear wheels of a circular shape and ofan interrupted or mutilated circular shape, respectively, the periods oftransition in the motion of the driven shaft of this gearing from thedecelerating and accelerating sections to the section in which itrotates together with the drive shaft because of the interengagement ofthe teeth of both gear wheels are very abrupt and are therefore hardlyattainable without jerking.

The French Pat. No. 1,114,409 discloses a gearing which overcomes thedisadvantages of the above-mentioned gearing insofar as it extends thelength of the stopping period of the driven shaft by providing a singleroller which, after the rotation of the driven shah is retarded up toits stop, disengages from one of two sections and, after carrying out arotary movement about an angle of, for example, 150, engages with theother cam section so as to re-start and accelerate the driven shaft. Inorder to lock the driven shaft during the stopping period, this gearingrequires additional locking disks which increase the cost of the gearingand also its susceptibility to trouble.

In order to dispense with these locking disks, the applicant of theabove-mentioned French patent discloses in a subsequent French patent ofaddition, No. 70.645 an improvement of the gearing according to his mainpatent in which the driven shaft of this gearing is only provided with asingle cam groove into which a single roller engages which is mounted onthe drive shaft. The stopping area of this cam groove extendsconcentrically to the drive shaft and thus permits the continuousmovement of the roller for an angular distance of, for example, withinwhich the cam element containing the cam groove and thus also the drivenshaft are not taken along so that during this period the driven shaft isstopped. By designing this stopping area of the cam groove so as toextend concentrically to the drive shaft, the cam element is supposed tobe locked so as to prevent its turning about the driven shaft relativeto which the stopping area of the cam groove does not extendconcentrically. This locking of the driven shaft during the stoppingperiod is, however, in actual practice not as effective as it may appeartheoretically since due to the necessary tolerances there remains acertain amount of free play which pennits the driven shaft during thestopping period to move, for example, slightly in the reverse directionif it is acted upon by forces which tend to effect such a reversemovement. Still more important is, however, the fact that this lockingaction remains effective only as long as the drive shaft continues torotate or is held locked in its stopped position. lf this does notoccur, the drive shaft may be turned by the driven shaft. Therefore, ifthe drive shaft is stopped but not locked in its stopped position, thelocking action upon the driven shaft will not be effective.

Furthermore, the associated gears on the drive shaft and the drivenshaft of the last mentioned gearing which interengage with each otherfor common rotation have a shape somewhat similar to that of an ellipsewith the exception of an arcuate toothless sector between the ends ofthe elliptical part of each gear. The transition of the velocity curveof the gearing at each end of the toothed parts of the elliptical gearsto the velocity curve of the gearing during the engagement ordisengagement of the roller with or from the cam groove is tangential,as seen in a velocity diagram of the driven shaft. In this manner it ispossible to effect a completely smooth transition between the commonrotary movement of the two shafts and the retarding and acceleratingperiods in the movement of the driven shaft, respectively. Although thisknown gearing substantially fulfills most of the above-enumeratedrequirements which a gearing according to the invention should fulfill,it does not fulfill the requirement that the driven shaft be locked whenit is in its stopped position and the drive shaft is also stopped butnot locked in its stopped position.

It is therefore the particular object of the present invention toprovide a gearing for converting the constant rotation of a drive shaftinto an intermittent rotation of a driven shaft, which gearing complieswith all of the requirements as mentioned in the beginning and thereforehas not only all of the advantages of the last mentioned known gearingbut also the advantage of positively locking the driven shaft when it isin its stopped position and when the drive shaft is also stopped but notlocked in its stopped position.

For attaining this object, the invention provides such amotion-converting gearing which comprises a drive shaft and a drivenshafi, a substantially elliptic drive gear secured to the drive shaftand a substantially elliptic driven gear secured to the driven shaft.Each of these gears has a toothed section and a toothless section whichis connected to the beginning and end of the toothed section. Thesetoothed sections of the two gears are adapted to interengage with eachother for a common rotation of both shafts. The gearing furthercomprises a roller support which is secured to the drive shaft and has apair of anti-friction rollers rotatably mounted thereon the axes ofwhich are disposed within planes which are spaced at radial distancesfrom the axis of the drive shaft. The driven shaft further carries a cammember which has a first decelerating curved cam groove and a secondaccelerating curved cam groove at opposite sides of the centrallongitudinal axis of the cam member. Each of these grooves has an openinner end near the driven shaft and another open outer end remote fromthe driven shaft, and these grooves are respectively defined by firstand second outer and inner guide walls. The inner end of the firstgroove is adapted to receive the first roller and this groove is adaptedto be guided by the first roller during its travel from the end of thetoothed section of the driven gear near the axis of the driven shaftuntil this roller leaves the outer end of the first groove, whereby therotation of the cam member and the driven shaft is decelerated from thecommon rotation up to a stopped position in which the first roller islocated at the outer end of the first groove. The second groove in thecam member is adapted to receive the second roller from the stoppedposition at the outer end of the second groove and is adapted to beguided by the second roller into the outer end and along the secondgroove to the beginning of the toothed section of the driven gear nearthe axis of the driven shaft until it leaves the inner end of the secondgroove, whereby the rotation of the cam member and the driven shaft isaccelerated from the stopped position to the common rotation of bothshafts. When the first roller is in the stopped position of the cammember and the driven shaft is at least about to leave the outer end ofthe first groove, the second roller is at the same time at least aboutto enter the outer end of the second groove. The inner walls of bothgrooves have a common cam-shaped end portion which connects the outerends of these inner walls to each other and extends in the stoppedposition so far between and in engagement with both rollers that thedriven shaft while stopped will be positively locked for a period up toa larger than momentary part of each complete revolution of the driveshaft. The outer ends at least of the inner wa ls adjacent to theconnecting end portion are made of a shape so that during the stoppedand locked period the first roller when leaving the outer end of thefirst groove will engage with but not move the inner wall of the firstgroove, while the second roller when entering the outer end of thesecond groove will engage with but not move the inner wall of the secondgroove It is therefore an important feature of the invention that withinthe stopping period both rollers are in engagement with the outer endsof the inner cam walls and thereby exert a locking action upon the cammember and thus also on the driven shaft. At least during a substantialpart of the stopping period the first roller leaving the first groovestill engages with the inner wall thereof, while the second rollerentering the second groove already engages with the inner wall of thesecond groove. During this time, the outer end portion of both innergrooves is located between and engages with the two rollers and thuslocks the driven shaft against any rotary movement. If in this positionthe drive shaft is also stopped, it cannot possibly be moved by thedriven shaft by means of the cam member. The cam member is thereforepositively locked also at this time by the two rollers.

Depending upon the desired length of the stopping period, the planeintersecting the axes of the two rollers may either intersect the axisof the drive shaft or be offset from this axis in the direction towardthe axis of the driven shah. More preferably, however, this plane islocated beyond the axis of the drive shaft, as seen from the axis of thedriven shah. Of course, when the two rollers are in locking engagementwith the cam grooves, only the length of the inner walls is ofimportance upon which both rollers engage during the locking period,that is, during at least a part of the length of the desired stoppingperiod. As regards this length, the points of contact between therollers and the cam grooves are therefore of importance.

The radial distance between the rollers and the axis of the drive shaftis preferably made of such a size that the peripheral surfaces of therollers are tangential to the pitch line of the toothed section of thesubstantially elliptic drive gear. The two substantially elliptic gearshave preferably equal pitch lines. According to a preferred embodimentof the invention, the inner walls of the grooves of the cam memberadjacent to the inner ends thereof are tangential to the pitch line ofthe toothed section of the driven gear.

The operation of the gearing according to the invention proceeds asfollows: Assuming that the driven shaft is in its stopped position, itwill at first be driven by the rollers engaging with the cam memberuntil the substantially elliptic tooth sectors of the two gears engagewith each other. The acceleration and deceleration of the driven shaftare therefore effected by the cam member in cooperation with therollers. The greatest load may, of course, be taken up by the toothedsections of the gears. Due to the fact that the transition of thevelocity line of the cam grooves into the velocity line of thesubstantially elliptic gear segments occurs tangentially, the transitionbetween the accelerating or decelerating periods and the common rotationof both shafts occurs smoothly and without jerking. By making the camgrooves of a suitable shape, it is also possible to effect thetransition between the deceleration of the driven shaft and the stoppingperiod and the restarting and subsequent acceleration of the drivenshaft to be smooth and without anyjerking.

The gearing according to the invention is preferably designed to attainstopping periods of the driven shaft amounting to about 10 percent ofone complete revolution of the drive shaft. it is, however, alsopossible to attain considerably longer stopping periods during eachrevolution of the drive shaft. A very secure locking effect during theparticular stopping period as desired may be attained by making theouter ends of the inner cam walls of a suitable shape, and by making thedistance between the plane intersecting the axes of the rollers and theaxis of the drive shaft and also the distance between the foci of theellipses of the substantially elliptical gears of suitable sizes.Depending upon the particular shapes and dimensions of the mentionedparts which might be chosen, it is possible to attain any desiredvelocity line of the motions of the driven shaft so that the speeds ofthe individual parts of the rotation of the driven shah and the lengthof its stopping periods may be varied so as to be in accordance with thedesired conditions.

An important advantage of the present invention is also the fact thatthe locking action as previously described may be attained without anyadditional locking means, such as locking disks or the like, as wererequired prior to this invention, that the entire gearing is of a verysimple, inexpensive, and reliably operating construction, that it may bemade of a small size and low weight, be built economically even if onlya small number of these gearings are required for a particular purpose,and be easily designed for being installed in and employed for theoperation of many different machines.

It is another feature of the present invention that it permits theroller support on the drive shaft which of the drive gear to be providedin the form of a worm wheel with which a worm shaft engages which isdriven by a motor or other driving means. In this manner it is possibleto attain a very slow intermittent rotation of the driven shaft. Thetorques which are to be reduced during the deceleration of the drivenshaft may then be taken up by the worm shaft. This is especially ofimportance if very strong torques acting upon the driven shaft are to becontrolled.

The gearing according to the invention permits the complete torque to betransferred in any position of the rotation of the gearing because nocritical position occurs. During the stopping period of the driven shaftthe motor driving the gearing may be easily retarded or switched off,especially if this motor is a brake motor of a conventional type. Thedriven shaft is then locked by means of the two rollers. If a timingrelay is then employed, the stopping periods may be made of any desiredlengths and be maintained very accurately.

The features and advantages of the present invention will become furtherapparent from the following detailed description thereof which is to beread with reference to the accompanying diagrammatic drawings, in which:

FIG. 1 shows a horizontal section of a gearing according to theinvention, as seen from above;

FIG. 2 shows a diagram of the velocity line of the elliptic driven gearand of the velocity line of the cam member;

FIGS. 3 to 6 show cross sections which are taken approximately along theline III III of FIG. I and in which FIG. 3 shows the gearing without itshousing in the stopped position of its driven shaft; FIG. 4 in theposition in which the first teeth of the two elliptic gears engage witheach other, FIG. 5 in a central position of engagement of the ellipticgears, and FIG. 6 in the position in which the last teeth of theelliptic gears engage with each other; while FIGS. 7 to 9 show enlargeddiagrammatic elevations of three modifications of parts of the gearingaccording to the invention.

As illustrated in the drawings, the motion-converting gearing accordingto the invention comprises a gear housing 12, as shown in FIG. I, inwhich a drive shaft 1 and a driven shaft 2 are rotatably mounted. Driveshaft I which may rotate at a uniform speed either in the clockwise orcounterclockwise direction carries a substantially elliptic gear 3 and aroller support 5 which, in turn, carries two opposite anti-frictionrollers 7 and 8. The driven shaft 2 likewise carries a substantiallyelliptic gear 4 which has the same size and shape as the gear 3, and acam member 6 which is provided with a cam track 9 which is composed oftwo cam grooves 90 and 9b which extend symmetrically to the centrallongitudinal plane of cam member 6 and are defined by inner cam wallsand outer cam walls 11. As indicated by the diagram in FIG. 2, thegearing is designed so that the velocity line W of each cam groove 90and 9b merges tangentially into the velocity line H of the elliptic gear4. The entire velocity ratio during one revolution therefore extends inthe form of a sinusoidal curve.

When the gearing is in the stopped or basic position as shown in FIG. 3,the centers of the toothless sections of the elliptic gears 3 and 4 faceeach other and the two opposite rollers 7 and 8 engage upon the outerends of the inner cam walls 10. If the drive shaft 1 is then turned, forexample, in the clockwise direction, as indicated by the arrow la,roller 8 will pass into the outer end of the cam groove 9b and duringthe further rotation of drive shaft I, roller 8 will take along the cammember 6 in the direction of the arrow 2a by rolling along the inner camwall 10 of cam groove 9b until the teeth of the elliptic gears 3 and 4interengage with each other, as shown in FIG. 4.

During the further rotation of drive shafi l, the driven shaft 2 will bedriven by the engagement of the teeth of gears 3 and 4 until these gearsare turned to the position as shown in FIG. 6 and the other roller 7enters the inner end of the other cam groove 9.4. During the furtherrotation of drive shaft 1, roller 7 will roll along and act upon theouter cam wall I] of cam groove 9a and take along the cam disk 6 in thedirection of the arrow 2a until the gearing arrives again in its basicposition as shown in FIG. 3. This cycle of the motions of the drivenshaft 2 is repeated during each complete revolution of drive shah 1during which the driven shaft 2 first starts to move gradually from itsstopped position and then accelerates until the teeth of the two gears 3and 4 engage with each other, and when the teeth of the two gears againdisengage, the driven shaft 2 decelerates until it arrives again in itsbasic stopped position.

In order to attain a smooth transition between the cam grooves and thetoothed parts of the gears 3 and 4, the central longitudinal plane ofthe cam disk 6 is disposed within the common plane connecting the axesof the two shafts l and 2 when the gearing is in the position as shownin FIG. 3, while the plane connecting the axes of the two rollers 7 and8 extends at a right angle to the first mentioned plane. The inner camwalls I0 of the two cam grooves and 9b extend tangen tially from thepitch line of the toothed part of the elliptic gear 4. Cam disk 6 andthus also the cam walls 10 and 11 then extend further up to a line whichis located beyond the drive shaft 1. The inner cam walls 10 approacheach other so far that between the rollers 7 and 8 they extendtangentially to the outer diameter of these rollers, while the outer camwalls ll are spaced from the corresponding points of the inner cam walls10 at a distance which is substantially equal to the diameter of therollers 7 and 8.

The radial distance of the rollers 7 and 8 from the axis of drive shaft1 is made of such a size that the outer diameter of the rollers 7 and 8is tangential to the pitch line of the associated elliptic gear 3. Theplane extending through the axes of the two rollers 7 and 8 may thenextend through the axis of drive shaft 1 or it may be located at one orthe other side of this axis.

Due to the tangential transition of the movable elements of the gearinginto and out of engagement with each other, all of the motions of thegearing are very smooth and occur without any jerking and the gearingtherefore operates almost without noise.

The gearing according to the invention may be very easily designed sothat the stopping period of the driven shaft 2 may last for a rotarymovement of the drive shaft 1 for an angular distance between 0 and 30and more of one complete revolution thereof and, for example, to about10 percent of such a revolution. This stopping period is attained bymaking the cam grooves 90 and 9b and their walls 10 and 11 of a suitableshape, by making the distance between the common plane of the axes ofrollers 7 and 8 and the axis of drive shaft 1 of a suitable size, and bymaking the gears 3 and 4 of a suitable elliptical shape or by spacingthe foci of their ellipses at a suita ble distance from each other. Ifthe rollers 7 and 8 as seen in their position according to FIG. 3 arespaced at a still greater distance from the axis of drive shaft 1 andthe cam grooves are shaped accordingly, and if the drive shaft 1 is thenturned in the clockwise direction of the arrow la, roller 8 will nottake the cam disk 6 along as quickly as it would do if it was spaced ata smaller distance from the axis of drive shaft 1. Consequently, thegearing may be designed so as to attain stopping periods of differentlengths.

In the velocity diagram according to FIG. 2, the stopping period lasts,for example, for an angular distance of about 5 of one revolution ofdrive shaft 1 from the position as shown in FIG. 3. This period may beeither increased or reduced so as to last for an angular distance ofabout 0 to 10 percent and more of one complete revolution of driveshaft 1. The cam grooves 9a and 9b are then to be designed accordinglyand must always start from the pitch line of the elliptic gear 4. Thelonger the stopping period is to be made, the more rapidly and closelythe cam grooves 90 and 9b must approach each other toward their plane ofsymmetry. This may be extended until the material between the two camgrooves 90 and 9!) becomes too thin for practical purposes at both sidesof the central longitudinal plane of the cam member 6. An example of theshape of the cam grooves which results in a longer stopping period isindicated in dot-and-dash lines at 9' in FIG. 3.

For a smooth operation of the gearing according to the invention it isimportant that, when, for example, the roller 8 enters the cam groove91), it will immediately engage with the inner cam wall 10 of thisgroove without, however, at first moving the same. For a certain lengthof the stopping period, the inner cam walls therefore extend so farbetween the two rollers 7 and 8 that the cam member 6 will be locked soas to prevent any independent rotary movement of its own. If thestopping period amounts to about 5' of one revolution, as provided forin FIG. 3, this length of the two cam grooves 90 and 9b in which bothrollers are in engagement with the inner cam walls 10 is very short andit is therefore hardly noticeable in this drawing. FIGS. 7 to 9 showenlarged illustrations of the principle according to which the rollerwhich is to enter the respective outer end of a cam groove will at firstengage with the inner wall thereof without, however, at first moving thesame.

The drive shaft 1 and the driven shaft 2 are only indicateddiagrammatically in FIGS. 7 to 9, while for a clearer illustration thegear segments are omitted therein entirely. Together with the driveshaft 1 the roller support 5, as indicated by heavy dot-and-dash lines,revolves, for example, in the same manner as shown in FIG. 3, that is,in the direction of the arrow la. On this roller support 5 the rollers 7and 8 are rotatably mounted. The plane which connects their axes extends in FIG. 7 at the side beyond the axis of drive shaft 1, as seenfrom the driven shaft 2, in FIG. 8 it extends through the axis of driveshaft 1, while in FIG. 9 it extends at the left side of the axis ofdrive shaft I. Although the cam grooves 9a and 9b are made of adifferent shape, the dimensions of the different parts as shown in FIGS.7 to 9 are enlarged to twice their sizes as shown in FIG. 3.

The rollers 7 and 8 are shown in each of FIGS. 7 to 9 in a symmetricalposition which corresponds to the center of a stopping period. In FIG.7, both rollers 7 and 8 will engage simultaneously within an angle a ofI upon the inner cam walls 10. During the outward movement of roller 7,the other roller 8 entering the cam groove 9b will at first not move theinner cam wall 10 of groove 9b, but only after it has traveled for thedistance of an angle (1/2 50 from the position as shown in FIG. 7. Cammember 6 will therefore not be taken along by the roller 8 until thistime and it will then be moved in the direction of the arrow 2a aboutthe driven shaft 2. The arrangement according to FIG. 7 thereforepermits the stopping period to last for an angular distance of 100 ofone revolution of drive shaft 1. During this period, both rollers 7 and8 engage upon the inner cam walls 10. Since the inner cam walls 10including their outer connecting end then project between and engagewith both rollers 7 and 8, any rotary movement of cam member 6 relativeto the driven shaft 2 will be prevented and the latter is positivelylocked.

In FIG. 8, the angle [3 within which both rollers 7 and 8 may engageupon the cam walls and prevent any rotary movement of the driven shaft 2amounts to 70, while in FIG. 9 this angle 1 amounts to 40. The outer endportion of the inner cam walls 10 according to FIGS. 8 and 9 whichconnects these walls to each other is made of a flatter shape than thatin FIG. 7 in order to effect the proper rolling movement. In any event,the locking action will be effective only during the angular distance ofa, ,B or 7. This locking action would therefore not be effected if theouter end portion which connects the two cam walls 10 to each otherwould be cut off, along the line 10' as indicated by a dot-and-dash linein each of FIGS. 7, 8 and 9. If a shorter stopping period or a shorterlocking period during the stopping period is desired, this may be easilyattained by varying the shape of the inner cam walls 10 accordingly. Theouter end portion may then be cut off to a still greater extent thanindicated by the line 10' in FIG. 9.

The desired length of the decelerating and accelerating periods may alsodetermine the particular shape of the elliptic gears 3 and 4. Thesmaller the distance is made between the two foci of the ellipse of eachof these gears, the shorter will be the accelerating and deceleratingperiods, although the smaller will also be the load to which the gearingmay be subjected. The smallest possible distance between the foci istherefore determined by highest admissible slope of the entire velocityline, as indicated in FIG. 2, while the largest possible distancebetween the fool is determined by the highest admissible distortion ofthe profile of the teeth of the elliptic gears 3 and 4. By making thecam track 9, the roller support together with the rollers 7 and 8, andthe distance between the foci of the ellipse of each gear 3 and 4 ofsuitable dimensions, it is therefore possible to design the gearingaccording to the invention without any difficulty in accordance with theparticular requirements which it should fulfill.

As already indicated, the new gearing may also be driven in eitherdirection and the driven shaft may therefore also rotate intermittentlyeither in the clockwise or counterclockwise direction. Consequently, thenew gearing may also be em ployed as a reversible gearing.

It is a further important advantage which may be attained by the presentinvention that, if the roller support 5 is provided in the form of aworm wheel 15, as indicated in dotted lines in FIG. 1, which is mountedon the shaft 1 carrying the gear 3, the gearing may also be driven bymeans of an associated worm shaft 14 which is connected to the drivingmotor or other driving means. In this manner it is possible to reducethe speed of rotation of the gearing according to the inventionconsiderably, while the full torque will be taken up by the worm gear inany position of the rotation of the gearing according to the inventionand the braking couples will be taken up by the worm shaft 14.

If the worm shaft 14 is driven by a brake motor of a conventional type,this motor will also be stopped without a load during the stoppingperiod of the driven shaft of the gearing. This means that during thestopping period of the driven shaft of the gearing the brake motor maybe switched off so that the gearing may also be stopped entirely. Bymeans of a timing relay it is then possible to switch on the motor againautomatically at any desired time.

From the foregoing description it is evident that the motionconvertinggearing according to the invention is applicable in different mannersand for many different purposes and also at different speeds anddifferent stopping periods of its driven shaft which may last from zeroto any desired length of time, and also by rotating its driven shaftafter each stopping period either in the same direction as previously orin the opposite direction.

Although our invention has been illustrated and described with referenceto the preferred embodiments thereof, we wish to have it understood thatit is in no way limited to the details of such embodiments but iscapable of numerous modifications within the scope of the appendedclaims.

Having thus fully disclosed our invention, what we claim is:

l. A motion-converting gearing comprising a drive shaft and a drivenshaft and adapted to convert a constant rotation of said drive shaftinto an intermittent rotation of said driven shaft, a substantiallyelliptic drive gear secured to said drive shaft, a substantiallyelliptic driven gear secured to said driven shaft, each of said gearshaving a toothed section and a toothless section connected to thebeginning and end of said toothed section, said toothed sections adaptedto interengage with each other for common rotation of both shafts, aroller support secured to said drive shaft, a pair of rollers rotatablymounted on said support and having axes within planes spaced at radialdistances from the axis of said drive shaft, and a cam member secured tosaid driven shaft and having a first decelerating curved cam groove anda second accelerating curved cam groove at opposite sides of the centrallongitudinal axis of said cam member, each of said grooves having anopen inner end near said driven shaft and another open outer end remotefrom said driven shaft and being respectively defined by first andsecond outer and inner guide walls, said first groove at its inner endadapted to receive said first roller and to be guided by the same fromthe end of said toothed section of said driven gear near the axis ofsaid driven shaft until it leaves the outer end of said first groove andfor thereby decelerating the rotation of said cam member and drivenshaft from said common rotation up to a stopped position at said outerend of said first groove, said second groove adapted to receive saidsecond roller from said stopped position at said outer end of saidsecond groove and to be guided by said second roller into said outer endand along said second groove to the beginning of said toothed section ofsaid driven gear near the axis of said driven shaft until it leaves saidinner end of said second groove and for thereby accelerating therotation of said cam member and driven shaft from said stopped positionto said common rotation, said first roller in said stopped position ofsaid cam member and driven shaft being at least about to leave saidouter end of said first groove, while at the same time said secondroller is at least about to enter said outer end of said second groove,said inner walls of both grooves having a common cam-shaped end portionconnecting the outer ends of said inner walls to each other andextending in said stopped position so far between and in engagement withboth of said two rollers that said driven shaft while stopped will bepositively locked for a period up to a larger than momentary part ofeach complete revolution of said drive shaft, said outer ends at leastof said inner walls adjacent to said connecting end portion having ashape so that during said stopped and locked period said first rollerwhen leaving said outer end of said first groove will engage with butnot move said inner wall of said first groove, while said second rollerwhen entering said outer end of said second groove will engage with butnot move said inner wall of said second groove.

2. A motion-converting gear as defined in claim 1, in which in saidstopped position a plane intersecting the axes of said rollers islocated beyond the axis of said drive shafi, as seen from the axis ofsaid driven shaft.

3. A motion-converting gear as defined in claim I, in which said rollersare radially spaced from the axis of said drive shaft at such a distancethat the peripheral surfaces of said rollers are tangential to the pitchline of the toothed section of said substantially elliptic drive gear.

4. A motion-converting gearing as defined in claim 1, in which saidtoothed parts of said substantially elliptic gears have equal pitchlines.

5. A motion-converting gearing as defined in claim I, in which saidinner walls of said grooves of said cam member adjacent to the innerends thereof are tangential to the pitch line of said toothed section ofsaid driven gear.

6. A motion-converting gearing as defined in claim 1, in which saidroller support fonns a worm wheel, and further comprising a worm shaftengaging with said worm wheel for driving said drive shaft.

* a a a a

1. A motion-converting gearing comprising a drive shaft and a drivenshaft and adapted to convert a constant rotation of said drive shaftinto an intermittent rotation of said driven shaft, a substantiallyelliptic drive gear secured to said drive shaft, a substantiallyelliptic driven gear secured to said driven shaft, each of said gearshaving a toothed section and a toothless section connected to thebeginning and end of said toothed section, said toothed sections adaptedto interengage with each other for common rotation of both shafts, aroller support secured to said drive shaft, a pair of rollers rotatablymounted on said support and having axes within planes spaced at radialdistances from the axis of said drive shaft, and a cam member secured tosaid driven shaft and having a first decelerating curved cam groove anda second accelerating curved cam groove at opposite sides of the centrallongitudinal axis of said cam member, each of said grooves having anopen inner end near said driven shaft and another open outer end remotefrom said driven shaft and being respectively defined by first andsecond outer and inner guide walls, said first groove at its inner endadapted to receive said first roller and tO be guided by the same fromthe end of said toothed section of said driven gear near the axis ofsaid driven shaft until it leaves the outer end of said first groove andfor thereby decelerating the rotation of said cam member and drivenshaft from said common rotation up to a stopped position at said outerend of said first groove, said second groove adapted to receive saidsecond roller from said stopped position at said outer end of saidsecond groove and to be guided by said second roller into said outer endand along said second groove to the beginning of said toothed section ofsaid driven gear near the axis of said driven shaft until it leaves saidinner end of said second groove and for thereby accelerating therotation of said cam member and driven shaft from said stopped positionto said common rotation, said first roller in said stopped position ofsaid cam member and driven shaft being at least about to leave saidouter end of said first groove, while at the same time said secondroller is at least about to enter said outer end of said second groove,said inner walls of both grooves having a common cam-shaped end portionconnecting the outer ends of said inner walls to each other andextending in said stopped position so far between and in engagement withboth of said two rollers that said driven shaft while stopped will bepositively locked for a period up to a larger than momentary part ofeach complete revolution of said drive shaft, said outer ends at leastof said inner walls adjacent to said connecting end portion having ashape so that during said stopped and locked period said first rollerwhen leaving said outer end of said first groove will engage with butnot move said inner wall of said first groove, while said second rollerwhen entering said outer end of said second groove will engage with butnot move said inner wall of said second groove.
 2. A motion-convertinggearing as defined in claim 1, in which in said stopped position a planeintersecting the axes of said rollers is located beyond the axis of saiddrive shaft, as seen from the axis of said driven shaft.
 3. Amotion-converting gearing as defined in claim 1, in which said rollersare radially spaced from the axis of said drive shaft at such a distancethat the peripheral surfaces of said rollers are tangential to the pitchline of the toothed section of said substantially elliptic drive gear.4. A motion-converting gearing as defined in claim 1, in which saidtoothed parts of said substantially elliptic gears have equal pitchlines.
 5. A motion-converting gearing as defined in claim 1, in whichsaid inner walls of said grooves of said cam member adjacent to theinner ends thereof are tangential to the pitch line of said toothedsection of said driven gear.
 6. A motion-converting gearing as definedin claim 1, in which said roller support forms a worm wheel, and furthercomprising a worm shaft engaging with said worm wheel for driving saiddrive shaft.